But PRS for Music, the group which compiled the figures and which is responsible for collecting and distributing royalties for 65,000 musicians and publishers, said it was too early to talk of a turning point in the industry.
The global music business has been shrinking steadily in recent years, hit by online piracy and the rapid decline in physical format sales like CDs, which have more than made up for the rapid growth in legal digital revenues.
"2009 was the first year in which the growth in revenues from the legal digital market compensated for the decline in revenues from traditional CDs and DVDs, though we remain cautious as to whether this represents a true turning point," said PRS for Music chief executive Robert Ashcroft.
"The next decade does, however, promise further growth in earnings from the legal digital market as well as the use of British music overseas."
And despite the growth in digital revenues last year, they still represent a small proportion of the overall market.
In 2009 online revenues grew 73 percent, or 12.8 million pounds to 30.4 million pounds, while earnings from CDs and DVDs fell by 8.7 million pounds.
The overall increase in the market was largely due to a sharp rise in British music use abroad, increasing 19 percent to 166.9 million pounds.
The UK music market fell slightly, hit by a drop in advertising revenues and the ringtone market among other factors.